WPR17FA108

The pilot's decision to turn toward the inoperative engine after conducting a low-level pass, which resulted in an aerodynamic stall at too low an altitude to recover. Contributing to the accident was the pilot's decision to perform the flight and the engine shut down demonstration with an inadequate airplane charging system and a known weak battery.

According to the surviving passenger, he, the pilot, and pilot-rated passenger departed on a cross-country flight over water; the pilot shut down the right engine to demonstrate how to restart an engine during flight. The pilot was unable to restart the engine using the starter due to a lack of electrical power. He then made several attempts to air start the engine by gaining altitude and diving the airplane down to use airflow to assist in rotating the engine. After two unsuccessful attempts, the pilot decided to descend to a lower altitude, fly to a remote airstrip, and use the handheld battery booster located in the baggage compartment after landing to start the engine. As the airplane approached the airstrip, the pilot made a low-level pass to check the condition of the runway surface. A witness saw the airplane at treetop level. As it reached the end of the airstrip, it dropped in altitude, banked to the right, and impacted the shoreline in a right-wing down, nose-down attitude. Instead of deciding to perform a low-level pass to an airstrip with one inoperable engine, the pilot should have handled the inoperative engine as a critical situation that necessitated landing the airplane immediately with minimal maneuvering. It is likely that, after the low-level pass, the pilot attempted to turn the airplane to maneuver for the runway and failed to adequately maintain sufficient airspeed or compensate for the asymmetrical thrust when he turned toward the inoperative engine which led to an aerodynamic stall and a loss of control. The examination of the wreckage revealed that, according to the positions of the landing gear, flaps, and their controls, the airplane had insufficient electrical power during flight. A friend who flew with the pilot on the day before the accident recalled that the pilot had installed a battery that had insufficient electrical power. The pilot then parked his motor vehicle near the airplane, plugged in the airplane's jumper cables, and successfully jumpstarted both engines from the vehicle's battery to continue that day's flight. It is likely that the battery was not replaced before the accident flight. The postaccident examination also found that the left engine alternator belt was not attached to the alternator, and no belt was recovered within the confines of the engine cowling. The alternator drive pulley was damaged and had a residue, indicating that the belt had not been attached to the left engine alternator for some time. Thus, the left alternator was not operational. The right engine alternator drive shaft rotated freely by hand, but the drive belt remained stationary with the crankshaft. The alternator drive belt was loose and excessively worn on the pulley contact area. The right engine inlet cowling section had rubber filings in the forward right interior surface. Rubber filings were also found on the back side of the starter ring gear and surrounding areas. The rubber filings were likely due to the loose fit of the belt on the pulley during engine operation. Given this evidence, the right engine alternator was probably intermittent with a loose belt. The airframe maintenance logbook indicated that the last annual inspection was accomplished 2 years and 9 months before the accident. The engine maintenance logbooks were not located; thus, it could not be determined when maintenance personnel last inspected the engine. Due to a modification to the cowling, it did not permit a visual examination of the front side of the engine and the alternator belts during a preflight walk-around inspection unless the upper cowling was removed. It is likely that the pilot was not aware that the alternators were inoperative and that the airplane was operating on battery power when he shut down the right engine in flight.

The State Medical Examiner's Office in Anchorage, Alaska, conducted autopsies on the pilot and pilot-rated passenger. The pilot's cause of death was reported as "Blunt impacts ..." The pilot-rated passengers cause of death was also reported as blunt impacts. Toxicology testing performed at the FAA Forensic Sciences Laboratory were negative on both the pilot and pilot-rated passenger for drugs, carbon monoxide and volatiles. At 1054, PAHN, located about 12 miles north of the accident site, reported the following conditions: wind from 150° at 7 knots, 10 miles visibility, clear skies, temperature 11°C, dew point 6°C, and an altimeter setting of 30.23 inches of mercury. The pilot, age 29, held a private pilot certificate with multiengine land and single-engine land and sea ratings. The pilot's most recent FAA third-class airman medical certificate was issued on January 30, 2013, with no limitations. On his medical application, the pilot reported that his total flight experience during the previous 6 months was 0 hours. The pilot's logbook was not located during the investigation. The airplane, which was manufactured in 1964, was an all-metal multiengine airplane that incorporated a semi-monocoque fuselage and empennage design. The airplane was equipped with fully cantilevered wings, electrically operated wing flaps, and electrically operated retractable tricycle landing gear. The airplane was powered by a Lycoming IO-320-B1A reciprocating engine on the left wing and a Lycoming LIO-320-B1A reciprocating engine on the right wing, and each was rated at 160 horsepower. The engines had 4 cylinders, 320-cubic-inch displacement, and fuel injection. The right engine had a counter-rotating kit installed. Each engine drove a Hartzell 2-blade, single-acting, hydraulically operated, constant-speed propeller with feathering capability. The airplane's electrical power was supplied by a 12-volt, direct-current, negative-ground system. The primary electrical source came from two 12-volt, 50-ampere alternators controlled by an overvoltage relay and voltage regulator. The overvoltage relay and voltage regulator were mounted on the aft bulkhead of the nose section. Secondary power was provided by a 12-volt, 35-ampere hour battery that supplies power for starting and was a reserve power source in the event of an alternator failure. The battery was mounted in a battery box located immediately aft of the baggage compartment. The amp/voltmeter instrument was installed in the instrument panel. Alternator isolation switches were mounted on the instrument panel. According to FAA records, the airplane's charging system was modified on December 8, 1993, by the removal of the generators and installation of an alternator charging system in accordance with Supplement Type Certificate (STC) SA334SW. If both alternators were inoperative, the airplane battery would be the only remaining source of electrical power. If the airplane battery were depleted and electrical power was not available, the Piper Twin Comanche PA-30 Pilot's Operating Handbook (POH) stated that the pilot must land with the flaps in the retracted position and must initiate the manual gear extension procedure and that the final approach landing speed must not exceed 100 mph or 87 knots. The airplane was also modified with LoPresti front engine cowlings in accordance with STC SA3302SO. The cowling modification would not have permitted a visual examination of the front side of the engine and the alternator belts during a preflight walk-around inspection unless the upper cowling was removed. The last entry in the airframe maintenance records was on August 20, 2014, when the last annual inspection was accomplished. At that time, the airplane had accumulated a total of 4,769 flight hours. No engine maintenance records were found. The airplane's Hobbs meter was not found in the wreckage. Due to impact damage to the cabin's digital instruments, the tachometer time at the time of the accident could not be determined. The impact site was located on the western tidal flats of the Chilkat Inlet, about 1/4-mile northeast of the north end of the airstrip at Glacier Point. The initial on-scene examination of the airplane by the NTSB-IIC and a Federal Aviation Administration inspector revealed impact damage consistent with a right-wing-down, nose-down attitude during ground impact. The airplane remained intact, all flight control surfaces were accounted for, and cable control continuity was confirmed. The landing gear was in the down position, and the landing gear position switch was in the down position. The landing gear extension motor release arm was found in the disengaged position. The emergency landing gear extension handle was removed from its stowed position and installed in a socket on the emergency disengage control. The flaps were in the up position and the flap lever was in the down position. Both engines separated from their wing mounts and remained partially attached to their wings by control cables and tubing. One of the left propeller blades was in a feathered/high pitch position and the other blade was rotated toward a high pitch position that was beyond the feathered position. Both blades exhibited leading edge gouging, twisting toward high pitch and bending in the forward/thrust direction. Heavy chordwise/rotational scoring damage was isolated to the face side of both blades. One blade tip had fractured and separated; the separated tip was recovered at the crash site. The right propeller was found with both blades in the feathered position. One blade was bent rearward with no remarkable twisting, and one blade had no remarkable damage. The elevator trim actuator was found in the full nose-down position and the rudder trim indicator was in the nose-left position. The wreckage was relocated to a hangar at PAGS, and examination of the wreckage showed that the right engine crankshaft propeller flange was bent to one side and that the rocker covers had impact damage. The right engine's exterior surfaces had a dark oily residue. Oil residue was observed in the area of the alternator pulley and belt. The right engine alternator was undamaged and secure, and no signatures suggested that the alternator was repositioned during the accident sequence. The alternator electrical wiring remained secure at the terminals. The alternator drive pulley rotated freely by hand, and the drive belt remained stationary with the crankshaft. The right engine alternator drive belt was loose when examined and was subsequently removed from the engine. The belt was excessively worn on the pulley contact area as shown in Figure 2. A spare alternator drive belt was found stowed to the engine; the stowed belt shared the same part numbers as the worn belt (Napa Premium XL 25-7365). According to the alternator STC installation instructions, a Franklin (P/N 14883) or a Goodyear 5L380 belts should be used. Figure 2-Right Engine Alternator Belt The right engine inlet cowling section had rubber filings in the forward right interior surface. Rubber filings were also found on the back side of the starter ring gear and surrounding areas.The left engine alternator was undamaged and secure, and no signatures suggested that the alternator was repositioned during the accident sequence. The alternator electrical wiring remained secure at each terminal. No belt was attached to the alternator pully, and no belt was recovered within the confines of the engine cowling. The alternator drive pulley forward face had impact damage, bending the edge of the forward face aft into the location where the drive belt would be positioned. There was no corresponding damage to the engine cowling in the area of the alternator pulley that would have resulted in damage to the alternator pulley. The alternator drive shaft rotated freely by hand. The alternator housing was covered in surface corrosion consistent to being submerged